Owing to their advantages such as lightweight, thin-profile, energy-saving, and no radiation, flat panel display devices such as liquid crystal display (LCD) devices have gradually replaced the conventional cathode ray tube (CRT) display devices as the mainstream display products. Currently, the LCD devices have found wide applications in various electronic apparatuses including digital TV sets, computers, personal digital assistants (PDAs), mobile phones and digital cameras.
Because an LCD panel does not emit light by itself, generally a backlight module must be disposed beneath the LCD panel to provide an area light source necessary for the LCD panel so that adequate brightness and an adequate contrast ratio are obtained to achieve the displaying function of the LCD device.
FIG. 1 is a schematic cross-sectional view of a conventional backlight module. As shown in FIG. 1, the conventional backlight module 100 comprises a backplate 110, a reflective sheet 120, a light guide plate 130, a light source 140 and a heat dissipating aluminum extruded piece 150. The backplate 110 comprises a baseplate 111, four side plates 112, and four connecting portions 113 for connecting the baseplate 111 with a corresponding one of the side plates 112 respectively. The reflective sheet 120 and the light guide plate 130 are disposed on the baseplate 111 in sequence. The light source 140 is disposed opposite to the light guide plate 130 so that light emitted by the light source 140 is guided into the light guide plate 130 to be transformed into an area light source. Additionally, the heat dissipating aluminum extruded piece 150 is disposed between the light source 140 and the backplate 110 to dissipate heat generated by the light source 140 and to fix the light source 140, and portions of the heat dissipating aluminum extruded piece 150 may also be used to support the reflective sheet 120 and the light guide plate 130.
However, the heat dissipating aluminum extruded piece 150 is relatively costly, and is unable to fix positions of the light source 140 and the light guide plate 130 relative to each other accurately, which leads to a low light coupling efficiency. Moreover, owing to advancement of the light source packaging technologies and improvement of performance of thermally conductive materials, it becomes unnecessary to dispose the heat dissipating aluminum extruded piece 150 in order to dissipate heat generated by the light source 140. Accordingly, an urgent need exists in the art to provide a novel backlight module structure that can solve this problem.